1. Field of the Invention
This invention relates to a magnetic head device for recording and/or reproducing data on a signal recording surface of a disc-shaped recording medium and a method for producing the magnetic head device.
2. Description of the Related Art
Disc drive devices on recording/reproducing data for a signal recording surface of a disc-shaped recording medium, such as a flexible disc, have been widely used in office computers and word processors, to say nothing of personal computers.
One such disc drive device has a magnetic head device with which to recording and/or reproducing data. This magnetic bead device carries a head chip on the distal end of each of two supporting arms so that the head chips face each other. The disc-shaped recording medium is sandwiched between the head chips for recording/reproducing data on oppositely facing signal recording surfaces.
The recent tendency in the disc-shaped recording medium is high density recording. In keeping up with this trend, the disc drive device for recording/reproducing the disc-shaped recording medium has also been improved correspondingly. That has been, the disc drive device is improved so as to have a driving system for rotationally driving the disc-shaped recording medium more speedily or a magnetic head device capable of forming recording tracks at a finer track pitch.
Specifically, the flexible disc, now in use, is recorded/reproduced as the magnetic head device is run in rotation in sliding contact with the signal recording surface of the disc. According to a recent proposal, the flexible disc in current use is recorded/reproduced with a high recording density of tens to hundreds of Mbytes. For recording/reproducing the flexible disc with this high recording density, a magnetic head device is used in which the flexible disc is run in rotation at a high speed and in which a head portion is slightly floated from the signal recording surface.
For recording/reproduction at different recording densities, different magnetic head devices are required. However, use of plural disc drive devices is laborious and expensive. It has thus been proposed to use a disc drive device capable of recording/reproduction with two sorts of the recording densities, namely a disc drive device having lower order compatibility.
The disc drive device exhibiting this lower order compatibility has a low order mode magnetic head for recording/reproduction adapted for having a sliding contact with the flexible disc and an upper order magnetic head for recording/reproduction adapted for being floated from the flexible disc.
With this magnetic head device, the flexible disc facing surface of the magnetic head device has two rails extending parallel to the disc running direction in order to cause the head portion to be floated slightly from the signal recording surface of the flexible disc for recording/reproduction in the upper order mode. By running the flexible disc at an elevated speed, there is generated a so-called air film between an area delimited between these two rails and the flexible disc surface to cause the head to be floated slightly.
In this magnetic head device, the width of these two rails or the separation therebetween affects the floating characteristics of the magnetic head device significantly. In this magnetic head device, the two rails formed on the flexible disc facing surface need to be formed to an extremely narrow tolerance.
In the above-described magnetic head device, the two rails are formed by bonding plural components, such as a head chip having a magnetic head for the upper mode or a head chip having a magnetic head for the lower mode, to form a chip assembly, and by grinding a flexible disc facing surface of the chip assembly to produce the above-mentioned two rails. The magnetic head of the upper mode faces one of the rails, with the magnetic head of the lower mode facing the other rail.
However, since the chip assembly is ground for forming these two rails, the boundary portion between the two chips tends to be cut off. In particular, if the junction surface is exposed on the two rails, the exposed portion tends to be fractured.
If the rail is partially fractured in this manner, the flexible disc tends to be damaged by resulting fractured pieces. Moreover, if the rails are fractured partially, the rail width cannot be set to a defined magnitude, thus affecting floating characteristics of the magnetic head device.